G++ Causing Struct Redefinition Errors in "type_traits.h" and Other Include Files

RonFAA

11/28/23, 8:21 PM

I have "been tasked" with trying to build old software (VERY old software, in fact, not compiled since 2014) on our newer platform, specifically using g++ 9.4.0 in Ubuntu 20.04. While doing so, I have encountered a number of errors, all of them occurring inside some of include files from "/usr/include/c++/9". The offending files are type_traits.h, bits/allocator.h, bits/basic_string.h, and bits/alloc_traits.h.

The build output looks like this:

make -C /home/schudall/TDWR_Appl_LocalUB/csci04/csc25
make[1]: Entering directory '/home/schudall/TDWR_Appl_LocalUB/csci04/csc25'
/usr/bin/g++ -c -I/home/schudall/TDWR_Appl_LocalUB/csci04/csc20 -I/home/schudall/TDWR_Appl_LocalUB/csci04/csc25  -Dvolatile= -O2 -Di586 -Wall -Wno-unused -DWX_MULTITHREADED -D_REENTRANT WxBase.C -o LINUX/WxBase.o
In file included from /usr/include/c++/9/bits/move.h:55,
                 from /usr/include/c++/9/bits/nested_exception.h:40,
                 from /usr/include/c++/9/exception:144,
                 from /usr/include/c++/9/ios:39,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from WxBase.C:33:
/usr/include/c++/9/type_traits:506:12: error: redefinition of ‘struct std::is_function<_Res(_ArgTypes ...)>’
  506 |     struct is_function<_Res(_ArgTypes...) volatile _GLIBCXX_NOEXCEPT_QUAL>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/usr/include/c++/9/type_traits:458:12: note: previous definition of ‘struct std::is_function<_Res(_ArgTypes ...)>’
  458 |     struct is_function<_Res(_ArgTypes...) _GLIBCXX_NOEXCEPT_QUAL>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is just one example of a number of other, similar errors being called out.

Point of disclosure: While I have some years' experience in programming C++, most of my experience has been in taking older code and transferring it to our systems. My C++ training dates to about 20-25 years ago (pre ANSI???). Also, I am newer to the Ubuntu environment.

With all that said, it looks like maybe I am not including something that these files need, or not passing in proper arguments to the compiler, or perhaps I have not installed all needed libraries to build on this device. OR the code is so deprecated, but I would not know where to begin cleaning things up with these errors. Reading the man pages has not helped :(

What I would like to ask is, if anyone with a deeper (and more up-to-date) base of experience than me can point me in the right direction, and give me some idea as to what I need to do to solve these issues? Thank you in advance!

0 + 5

g++

Ray

11/28/23, 8:45 PM

I've found that when you go to a newer version of C++, you sometimes get a more restrictive compiler because the standard has become more restrictive. i.e., it now doesn't allow what was previously allowed, which in the end helps the programmer. Ubuntu 20.04 seems to have g++ as far back as version 7 (see [here](https://packages.ubuntu.com/focal/g++-7)). Try an older version and see if that works. If it does, move up from that and maybe you'll find out which `gcc` breaks it. The modify the code as necessary. Instead of using a `Makefile`, find one file and focus on that first.

steeldriver

11/28/23, 10:18 PM

It's the `-Dvolatile=` preprocessor directive that's causing that particular error, I think

steeldriver

11/29/23, 12:14 AM

... so perhaps `make CXXFLAGS=-Uvolatile -C /home/schudall/TDWR_Appl_LocalUB/csci04/csc25` or `make CPPFLAGS=-Uvolatile -C /home/schudall/TDWR_Appl_LocalUB/csci04/csc25` would be worth a try (hard to guess without seeing the Makefile)

RonFAA

11/29/23, 6:15 PM

Thank you both for your responses. Will be trying this over the next few days and will get back to you with results!

RonFAA

12/6/23, 3:43 PM

Both of your suggestions were implemented and have apparently solved much of the problems encountered. Also dealing with namespace issues related to many of the iostream definitions, but that will simply require some "elbow grease" to clean up the old code and bring it up to date. Thank you both for your help.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: G++ Causing Struct Redefinition Errors in "type_traits.h" and Other Include Files

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